libjava/java/io/FilterReader.java

   1 /* FilterReader.java -- Base class for char stream classes that filter input
   2    Copyright (C) 1998, 1999, 2001, 2003, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.io;
  40
  41 /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
  42  * "The Java Language Specification", ISBN 0-201-63451-1
  43  * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
  44  * Status:  Believed complete and correct.
  45  */
  46
  47 /**
  48   * This is the common superclass of all standard classes that filter
  49   * input.  It acts as a layer on top of an underlying <code>Reader</code>
  50   * and simply redirects calls made to it to the subordinate Reader
  51   * instead.  Subclasses of this class perform additional filtering
  52   * functions in addition to simply redirecting the call.
  53   * <p>
  54   * When creating a subclass of <code>FilterReader</code>, override the
  55   * appropriate methods to implement the desired filtering.  However, note
  56   * that the <code>read(char[])</code> method does not need to be overridden
  57   * as this class redirects calls to that method to
  58   * <code>read(yte[], int, int)</code> instead of to the subordinate
  59   * <code>Reader} read(yte[])</code> method.
  60   *
  61   * @author Aaron M. Renn (arenn@urbanophile.com)
  62   * @author Warren Levy (warrenl@cygnus.com)
  63   */
  64 public abstract class FilterReader extends Reader
  65 {
  66   /**
  67     * This is the subordinate <code>Reader</code> to which method calls
  68     * are redirected
  69     */
  70   protected Reader in;
  71
  72   /**
  73     * Create a <code>FilterReader</code> with the specified subordinate
  74     * <code>Reader</code>.
  75     * The <code>lock</code> of the new <code>FilterReader</code> will be set
  76     * to <code>in.lock</code>.
  77     *
  78     * @param in The subordinate <code>Reader</code>
  79     */
  80   protected FilterReader(Reader in)
  81   {
  82     super(in.lock);
  83     this.in = in;
  84   }
  85
  86   /**
  87     * Calls the <code>in.mark(int)</code> method.
  88     *
  89     * @param readlimit The parameter passed to <code>in.mark(int)</code>
  90     *
  91     * @exception IOException If an error occurs
  92     */
  93   public void mark(int readlimit) throws IOException
  94   {
  95     in.mark(readlimit);
  96   }
  97
  98   /**
  99     * Calls the <code>in.markSupported()</code> method.
 100     *
 101     * @return <code>true</code> if mark/reset is supported,
 102     * <code>false</code> otherwise
 103     */
 104   public boolean markSupported()
 105   {
 106     return(in.markSupported());
 107   }
 108
 109   /**
 110     * Calls the <code>in.reset()</code> method.
 111     *
 112     * @exception IOException If an error occurs
 113     */
 114   public void reset() throws IOException
 115   {
 116     in.reset();
 117   }
 118
 119   /**
 120     * Calls the <code>in.read()</code> method.
 121     *
 122     * @return The value returned from <code>in.available()</code>
 123     *
 124     * @exception IOException If an error occurs
 125     */
 126   public boolean ready() throws IOException
 127   {
 128     return(in.ready());
 129   }
 130
 131   /**
 132     * Calls the <code>in.skip(long)</code> method
 133     *
 134     * @param numBytes The requested number of chars to skip.
 135     *
 136     * @return The value returned from <code>in.skip(long)</code>
 137     *
 138     * @exception IOException If an error occurs
 139     */
 140   public long skip(long num_chars) throws IOException
 141   {
 142     return(in.skip(num_chars));
 143   }
 144
 145   /**
 146     * Calls the <code>in.read()</code> method
 147     *
 148     * @return The value returned from <code>in.read()</code>
 149     *
 150     * @exception IOException If an error occurs
 151     */
 152   public int read() throws IOException
 153   {
 154     return(in.read());
 155   }
 156
 157   /**
 158     * Calls the <code>in.read(char[], int, int)</code> method.
 159     *
 160     * @param buf The buffer to read chars into
 161     * @param offset The index into the buffer to start storing chars
 162     * @param len The maximum number of chars to read.
 163     *
 164     * @return The value retured from <code>in.read(char[], int, int)</code>
 165     *
 166     * @exception IOException If an error occurs
 167     */
 168   public int read(char[] buf, int offset, int len) throws IOException
 169   {
 170     return(in.read(buf, offset, len));
 171   }
 172
 173   /**
 174     * This method closes the stream by calling the <code>close()</code> method
 175     * of the underlying stream.
 176     *
 177     * @exception IOException If an error occurs
 178     */
 179   public void close() throws IOException
 180   {
 181     in.close();
 182   }
 183
 184 } // class FilterReader
 185